After fighting with no debug working on gwt (yeah, believe me, tryied everything) and fighting hard with missing date/time daylight savings time horror stories, we decided to move gradually to Angular+. It is easy to integrate both Angular and gwt modules (not components) on same page by using iframes. We will do that until everything is rewritten in Angular. Few thounds dialogs and hundred custom components are being rewritten by the team. And thanks to our architecture (encouraged by gwt), we have zero business rewrite.
That's it, gwt is at the end of line here.
Of course Angular presents many obstacles that we will overcome using OO patterns thanks to typescript, which is a elegant language for its purpose.